Breakthrough on virus infecting rare and endangered parrots

Wednesday 5 Oct 2016

Australian researchers have unravelled
the molecular makeup of a virus threatening some of the world's most endangered
species, paving
the way for the potential development of a vaccine to save dwindling
populations of the Australian birds.

The research, led by Charles
Sturt University (CSU) scientists and published in the prestigious international
journal Nature Communications
overnight, revealed the structure of the smallest self-replicating virus behind
the beak and feather disease (BFD).

The virus causes a debilitating disease
affecting four rare species of native parrot, including the Western ground and
Orange-bellied Parrots, of which less than 50 remain in the wild.

CSU Professor in Biochemistry
Jade Forwood said, "We now have a unique way of thinking about the virus and
how it self-assembles. We know at the atomic level, the structure of the virus
and how it fits together."

CSU Professor in Veterinary
Pathobiology Shane Raidal said, "The finding is significant because, by confirming
how the viral structure forms, we can
begin to develop a vaccine to interrupt these processes."

The
BFD virus programs only two proteins to drive its replication and spread: one
to assist the reproduction of the viral DNA, and one to construct the outer
shell of the virus. This shell is built from 60 individual capsid proteins that
self-assemble and fit together in a highly specific and ordered arrangement
around the viral DNA.

The
outcomes of this research provide the atomic coordinates of approximately 200 000
atoms which make up the virus, and insights into how the viral DNA can bind to
the shell, ensuring the protection and delivery of the viral DNA.

At the Australian Synchrotron
in Melbourne, landmark research infrastructure of the Australian Nuclear
Science and Technology Organisation (ANSTO), the Micro Crystallography (MX2) beamline
produced X-rays more than a million times brighter than the sun to create
intricate diffraction patterns as light bounced off microscopic crystals of the
viral capsid proteins. This allowed the researchers to identify the locations
of the individual atoms and broader structure of the viral shells in stunning
3D detail.

The
research team, involving scientists from CSU, Monash University, the Australian Synchrotron, and Spain's National
Microbiology Centre and the Autonomous University of Madrid, have been working on the project
since 2009.

Along with the loss of habitat
and feral predators, the BFDV is one of the main threats to the affected
parrots, which also include the Norfolk Parakeet (Norfolk Island) and the Swift
Parrot (eastern and southern states). Infected birds face starvation and death
as their feathers moult and their beaks soften.

Professor Raidal said, "The
disease has caused significant problems, in particular, for the Orange-bellied
Parrot since 2006 when it reappeared in the captive recovery program.

"The Parrot is a small and vulnerable migratory bird which breeds only
on Tasmania's south-west coast, flying north to spend the winter in coastal Victoria
and South Australia, so we look forward to building on this work to find new
approaches to restoring their numbers in the wild."

Mr Barry
Baker, Chair of the national Orange-bellied Parrot Recovery Team said it's
important new and innovative fields of science work across conservation
projects to protect Australia's at-risk fauna.

"BFDV is an
awful disease, especially in small, short-lived species like Orange-bellied
Parrots – young birds with the virus stand little chance of survival in the
wild, and affected captive birds are often compromised, as the virus can affect
the bird's ability to fight off other health issues."

"Although
recent Orange-bellied Parrot recovery efforts have proven effective, in 2014
the wild population suffered from a spillover of BFDV (from another wild
species) and we believe there are currently less than 30 birds out there -
another outbreak of the disease in the wild would be a disaster, so the ability
to vaccinate would be a leap forward in parrot conservation, also benefitting
captive populations and our ability to release to the wild."

Professor
in Biochemistry Jade Forwood is an Australian Research Council (ARC) Research
Fellow (2013-2016) in the School
of Biomedical Sciences at CSU in Wagga Wagga.

Both
scientists are members of the Graham Centre for
Agricultural Innovation.For interviews with Chair of
Birdlife Australia's Orange-bellied Parrot Recovery Team, Mr Barry Baker, contact
John Peter on (03) 9347 0757.

National and
international partners for this research were the Australian Synchrotron and Monash
University in Victoria, and the Centro Nacional de Microbiologı and the Insituto
de Fısica de la Materia Condensada, Universidad Autonoma de Madrid, both in Spain.